/Engine/Source/Runtime/Engine/Classes/Components/SkinnedMeshComponent.h
Finds the closest bone to the given location
the name of the bone that was found, or 'None' if no bone was found
[FName](API\Runtime\Core\UObject\FName) FindClosestBone ( FVector TestLocation, FVector * BoneLocation, float IgnoreScale, bool bRequirePhysicsAsset ) const